Method of building a ship&#39;s hull



1967 H. c. GEORGII 3,304,901

METHOD OF BUILDING A SHIPS HULL Filed Sept. 20, 1965 United States Patent Office 3,304,9fll Patented Feb. 21, 1967 3,304,901 METHOD F BUILDING A SHIPS HULL Hans Christer Georgii. Rindogatan 42, Stockholm, weden Filed Sept. 20, 1965, Ser. No. 488,577 Claims priority, application Sweden, Sept. 21, 1964, 11,333/ 64 2 Claims. (Cl. 114-77) The present invention relates to a method for building a ships hull or a substantial portion of a ships hull of the type having a completely closed cross-section, that is the interior of the hull is on all sides surrounded by the skin of the hull. In particular the invention concerns a method of building ships hulls of a size considerably exceeding the largest ships built at present. In particular, it is contemplated to provide a method making it possible to build very large cargo vessels, especially tankers, of a type operating as submarine vessels in that the entire vessel is submerged, possible with exception for the upper portion of a superstructure. The invention is, however, not limited to the building of ships of this type but can also be used for building ships of a more conventional type and a size used today.

With the methods of ship building used to-day the ships hull is built on a stationary bed arranged on a slipway on the shore or in a dry or floating dock. Upon this stationary bed the ships hull is built in its natural position, that is with its fore-and-aft axis substantially horizontal. When building the ships hull upon the stationary bed the keel or the keel plates of the hull is at first laid out upon the bed, whereafter the hull is built piece by piece upwards from this keel in direction towards the deck of the hull. Alternatively, larger or smaller sections of the ships hull are prefabricated at some place removed from the bed itself and thereafter transported to the bed and put together to a complete hull. This previous building method involves considerable difficulties and costs when ships of large dimensions are to be constructed. The bed itself must have a size corresponding to the length of the ship to be built and will consequently require a considerable area and become very expensive, in particular if the bed is to include also a floating dock or a dry dock. Furthermore, extensive and expensive lifting and transporting equipments are required for the supply of the material for the ship to all points along the very long bed. As the cross section of the ships hull will increase together with the length of theship, considerable and serious problems will arise regarding to the strength of the hull during the building thereof, until the hull is completed and to a certain extent self-supporting. For the same reason extensive and heavy supporting means are necessary at the bed for supporting the hull during the building thereof. The launching of a ships hull of large dimensions is also a complicated and difficult operation, in particular when the hull is to be launched from a slipway.

The object of the present invention is therefore to provide a new and improved method of building a ships hull having a completely closed cross-section, which method eliminates the above-mentioned dificulties involved in the building methods previously used and which makes it possible to build ships hulls of the type defined having dimensions considerably larger than for the largest ships previously constructed.

The method according to the invention of building a ships hull having a completely closed cross-section comprises the steps of fabricating a comparatively short end section of the hull having a closed end and an opposite open end; floating said end section on the surface of a body of water with said open end facing upwards with the fore-and-aft axis in said end section of the hull substantially vertical and with the upper edge of said end section at a level above the surface of said water; progressively building the hull from the upper edge of said end section vertically upwards in a direction parallel to the fore-and-aft axis of the hull and progressively lowering the fabricated portion of the bull in concurrence with the building thereof by simultaneously filling a liquid, preferably water, into the fabricated portion of the hull so that it sinks vertically downwards in the surrounding water but is maintained substantially independently floating therein with its fore-and-aft axis substantially vertical and its upper edge above the surface of the surrounding water and with the weight of the fabricated portion of the hull substantially balanced by the upward thrust from the surrounding water; building the hull to its desired length and closing subsequently the upper end of the hull while leaving sufficient openings for removing the liquid present within the hull; removing the liquid present within the hull at least partially until the hull is independently floating in the body of water with its fore-and-aft axis substantially horizontal.

The method according to the invention eliminates all the difl iculties and disadvantages of the previously used methods for the building of ships hulls. Thus, for instance, the method according to the invention does not require any stationary bed having a length corresponding to the total length of the hull and provided with extensive and expensive equipments for supporting the entire weight of the hull. The working site proper will occupy a comparatively limited area, as its size is no longer determined by the total length of the hull but by its cross section. Due to this the equipment necessary for lifting and transporting :the building material to the different parts of the hull will be less extensive and expensive. The maximum lifting height required will also be reduced, as the upper end of the completed portion of the hull, where the construction work is carried out, can be maintained at a constant predetermined height.

Furthermore a difficult launching of the completed hull is avoided. When the hull has been built to its desired length the upper end thereof is preferably closed, for instance with a bulkhead, while leaving, however, sufficient openings for removing the liquid present within the hull, whereafter the liquid filled into the hull during the building process is removed therefrom completely or partially so that the hull will by itself float up to the water surface and assume a position with its fore-and-aft axis substantially horizontal. The shape or cross section of the hull can be so designed that the hull will automatically assume a position with its bottom down, when it floats up to the water surface with its fore-and-aft axis horizontal. Alternatively the interior of the hull can during the building thereof be partitioned into several mutually closed spaces or the outer skin of the hull can be constructed to comprise closed tanks, in which case some of these closed spaces or tanks respectively can be ballasted, for instance with water, in such a way that the hull is brought to assume a position with its bottom down.

As during the building of the hull a substantial portion and in the first hand the lowermost portion of the already completed portion of the hull is filled with water exerting a pressure from the inside on the skin of the hull counteracting the pressure exerted on the hull from the outside by the surrounding water, the problems concerning the strength of the hull are also considerably reduced when using the method according to the invention for the build ing of a ships hull.

The assemblage of the hull can of course be carried out in various ways when using the building method according to the invention. Thus for instance it is possible to add the skin of the hull and the necessary ribs, bulkheads and partition walls in the hull piece by piece to the upper end of the complete portion of the hull. Alternatively it is also possible of course to prefabricate larger or smaller sections of the hull in a manner substantially as previously used and thereafter trans-port the prefabricated portions to the site where the hull is built and attach the prefabricated sections to the upper end of the already completed portion of the hull.

In the case that the hold of the hull is divided by partition walls and bulkheads in several mutually closed spaces, it can in certain cases be preferable to fill only some of these spaces with water during the building of the hull.

It should be noted that the method according to the invention is not necessarily used for the construction of the entire hull of a ship, but it can for instance also be used only for the building of a major portion of the hull, in particular the substantially uniform portion of the hull comprising the cargo spaces. When this main portion of the hull has been built according to the method according to the invention, a forepart and an after part of suitable design and comprising the necessary machinery for the ship can be constructed and attached to the main portion of the hull in any suitable conventional manner.

In the following the invention will be further described with reference to the accompanying drawing, in which FIGS. 1-3 illustrate different stages of the building of a ships hull according to the method according to the invention.

FIG. 1 shows an end section of the hull to be built, which end section has been prefabricated in some suitable conventional manner and has its one end closed and its opposite end open. This end section is arranged floating with its open end facing upwards on the surface of a body of water having a depth exceeding the length of the hull to be constructed. A certain amount of water may be filled into this end section of the hull in order to bring the upper edge of the end section at a convenient height above the surface of the surrounding water. Pontoons arranged around the end section floating on the Water surface can serve as working platforms and a base for the necessary transport and lifting equipment. These pontoons have only to be dimensioned to support said lifting and transporting equipments and the necessary material and workmen during the building of the hull, as the hull itself is completely or to the major part supported by the upward thrust from the surrounding water. The completed portion of the hull is however preferably connected to the anchored pontoons in such a way that it cannot be moved by currents and wave motions in the water.

As illustrated in FIGS. 2 and 3 the hull is subsequently built from the upper edge of the prefabricated end section floating on the water surface vertically upwards in a direction parallel to the fore-and-aft axis in the hull, at the same time as water is filled into the prefabricated end section and the completed portion of the hull so that the completed portion of the hull i lowered vertically downwards into the water in concurrence With the building of the hull and so that the upper end of the completed portion of the hull is maintained at a desired constant level above the surrounding water surface.

When the hull has been completed to its desired length, the upper end of the hull is closed, preferably by means of a bulkhead, leaving, however, sufficient openings for the removal of the water present in the fabricated hull, whereafter this water is removed completely or partially from the hull so that the hull will float up to the water surface with it fore-and-aft aXis horizontal. Additional working processes for completing the ship can be carried out in any suitable conventional way.

In the above description of the invention it has been implied that the liquid filled into the completed portion of the hull during the building of the hull is water, though this 'will probably in most cases be advantageous, as water is always available without any costs at the building site, it is also possible to use other liquids than water. In certain cases it can, for instance with respect to the strength of the hull during the building thereof, be advantageous to use a liquid having a smaller density than water, as for instance oil or gasoline, so that a larger volume of liquid can be filled into the hull.

It has also been assumed implicitly that the hull is constructed of metal. It is, however, also contemplated according to the invention to use the method according to the invention for the building of ships hulls entirely or partially of other materials. In particular it is contemplated to use the method according to the invention for building ships hulls of concrete.

I claim:

1. A method of building a ship hull having a completely closed cross-section which comprises the steps of fabricating a comparatively short end section of the hull having a closed end and an opposite open end; floating said end section on the surface of a body of water with said open end facing upwards with the fore-and-aft axis in said end section of the hull substantially vertical and with the upper edge of said end section at a level above the surface of said water; progressively building the hull from the upper edge of said end section vertically upwards in a direction parallel to the fore-and-aft axis of the hull and progressively lowering the fabricated portion of the hull in concurrence with the building thereof by simultaneously filling a liquid, preferably water, into the fabricated portion of the hull so that it sinks vertically downwards in the surrounding water but is maintained substantially independently floating therein with its foreand-aft axis substantially vertical and its upper edge above the surface of the surrounding water and with the weight of the fabricated portion of the hull substantially balanced by the upward thrust from the surrounding water; building the hull to its desired length and closing subsequently the upper end of the hull while leaving ulficient openings for removing the liquid present within the hull; removing the liquid present within the hull at least partially until the hull is independently floating in the body of water with its fore-and-aft axis substantially horizontal.

2. A method as claimed in claim 1, wherein the interior of the hull is divided into mutually closed spaces and only certain of said spaces are filled with liquid during the building of the hull.

No references cited.

MILTON BUCHLER, Primary Examiner.

T. M. BLIX, Assistant Examiner. 

1. A METHOD OF BUILDING A SHIP''S HULL HAVING A COMPLETELY CLOSED CROSS-SECTION WHICH COMPRISES THE STEPS OF FABRICATING A COMPARATIVELY SHORT END SECTION OF THE HULL HAVING A CLOSED END AND AN OPPOSITE OPEN END; FLOATING SAID END SECTION ON THE SURFACE OF A BODY OF WATER WITH SAID OPEN END FACING UPWARDS WITH THE FORE-AND-AFT AXIS IN SAID END SECTION OF THE HULL SUBSTANTIALLY VERTICAL AND WITH THE UPPER EDGE OF SAID END SECTION AT A LEVEL ABOVE THE SURFACE OF SAID WATER; PROGRESSIVELY BUILDING THE HULL FROM THE UPPER EDGE OF SAID END SECTION VERTICALLY UPWARDS IN A DIRECTION PARALLEL TO THE FORE-AND-AFT AXIS OF THE HULL AND PROGRESSIVELY LOWERING THE FABRICATED PORTION OF THE HULL IN CONCURRENCE WITH THE BUILDING THEREOF BY SIMULTANEOUSLY FILLING A LIQUID, PREFERABLY WATER, INTO THE FABRICATED PORTION OF THE HULL SO THAT IT SINKS VERTICALLY 